AuroraRuntime/Include/Aurora/Utility/RateLimiter.hpp

/***
    Copyright (C) 2022 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: RateLimiter.hpp
    Date: 2022-2-8
    Author: Reece
***/
#pragma once

namespace Aurora::Utility
{
    struct RateLimiter
    {
        AuUInt64 nextTriggerTime {};
        AuUInt64 nsTimeStep {};
        bool noCatchUp {};

        inline RateLimiter()
        {

        }

        inline RateLimiter(AuUInt64 nsTimeStep)
        {
            SetNextStep(nsTimeStep);
        }

        inline auline void SetTargetTime(AuUInt64 timeAbsNs)
        {
            this->nsTimeStep = 0;
            this->nextTriggerTime = timeAbsNs;
        }

        inline auline void SetNextStep(AuUInt64 nsTimeStep)
        {
            this->nsTimeStep = nsTimeStep;
            this->nextTriggerTime = nsTimeStep + Aurora::Time::SteadyClockNS();
        }
        
        inline auline bool CheckExchangePass()
        {
            auto cur = this->nextTriggerTime;

            if (!cur)
            {
                return false;
            }

            if (cur <= Aurora::Time::SteadyClockNS())
            {
                if (this->nsTimeStep)
                {
                    return AuAtomicCompareExchange(&this->nextTriggerTime, GetLatch(), cur) == cur;
                }
                else
                {
                    return true;
                }
            }

            return false;
        }
        
        inline auline bool HasPassed()
        {
            if (!this->nextTriggerTime)
            {
                return false;
            }

            if (this->nextTriggerTime <= Aurora::Time::SteadyClockNS())
            {
                return true;
            }

            return false;
        }
        
        inline auline void Relatch()
        {
            if (this->nsTimeStep)
            {
                AuAtomicAdd(&this->nextTriggerTime, GetLatch());
            }
        }

    private:

        inline auline AuUInt64 GetLatch()
        {
            if (this->noCatchUp)
            {
                return this->nsTimeStep + Aurora::Time::SteadyClockNS();
            }
            else
            {
                return this->nextTriggerTime + this->nsTimeStep;
            }
        }
    };
};